2,4-dimethyl-3 methylene-1,4-pentadiene and polymer

ABSTRACT

2,4-Dimethyl-3-methylene-1,4-pentadiene has &#39;&#39;&#39;&#39;crossconjugation&#39;&#39;&#39;&#39; and homopolymerizes thermally to an elastomeric material.

United States Patent Blume 1 1 Jan. 14, I975 1 2,4-DIMETHYL-3 3,770,84011/1973 Shepherd".. .1 260/666 P 4/1974 Blumc 260/682METHYLENE-l,4-PENTADIENE AND POLYMER Inventor: Roe Calvin Blume,Wilmington, Del.

Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

Filed: 061. 9, 1973 Appl. No.2 404,790

Related US. Application Data Division of Ser. No, 231,395, March 2,1973, Pat. No. 3,806,551.

US. Cl. 260/677 R, 260/681, 260/682 Int. Cl. C07c 11/24 Field of Search260/677, 680, 682, 666 A,

References Cited UNITED STATES PATENTS 10/1966 Tonkyn 208/681 OTHERPUBLICATIONS Faradays Encyclopedia 1958, p. 181 3'mcthylcne-2,4-Dimethyl-Pentene41 Chemical Abstracts, Vol. 72, 1970, Alicyclic Compounds, Braker, 3070v.

Primary Examiner--Delbcrt E. Gant; Assistant Examiner-Juanita M. NelsonABSTRACT conjugation" and homopolymerizes thermally to an elastomericmaterial.

1 Claim, N0 Drawings 2,4-DIMETHYL-3-METHYLENE-1 ,4-PENTADIENE ANDPOLYMER This is a division, of application Ser. No. 231,395, filed Mar.2, 1973, now U.S. Pat. No. 3,806,551.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionconcerns the production of unsaturated alcohols by reacting an allenichydrocarbon with formaldehyde under non-acidic conditions.

2. Description of Prior Art Formaldehyde is known to react withunsaturated compounds. With ethylenic compounds, e.g., propylene,formaldehyde gives butane-1,3-diol in the presence of acid catalysts.Basic catalysts in the presence of formaldehyde have been used whencondensations such as the Cannizzaro or aldol reactions are desired buthave not been used for addition to carbon to carbon double bonds.

DESCRIPTION OF THE INVENTION It has now been found that a facile way ofproducing an unsaturated alcohol consists essentially in the step ofreacting a compound of the formula n cu -c-c-c-n i wherein wherein the Rgroups, alike or different, are selected from the group consisting ofhydrogen, alkyl and aryl of up to seven carbon atoms, with at least anequimolar amount of formaldehyde at a temperature of 135220C. underneutral or basic conditions. Preferably the sum of the carbons in all ofthe alkyl and aryl groups is no more than and generally no more thaneight.

Allenes included are tetramethylallene (2,4-dimethyl-2,3-pentadiene),tetraethylallene, l,2- butadiene, 2,3-pentadiene,3-methyI-1,2-butadiene, 2-methyl2,3-pentadiene, l-phenyl-l ,Z-butadiene,1 phenyl-2,3-pentadiene, and 2-phenyl-2,3-butadiene. Preferred istetramethylallene from which may be obtained the novel alcohol2-isopropenyl-3-methyI-2- buten-l-ol, and in turn, a dehydration product2,4- dimethyI-3-methylene-l ,4-pentadiene.

Tetramethylallene is readily available by thermal cracking ofdimethylketene dimer. Other allenes (1,2- dienes) are available by theprocedures known to the art (e.g., as summarized by Sandler and KaroOrganic Functional Group Preparations, Academic Press, New York, 1971).Methods for the production of allenes include reaction of an olefin witha trihalomethane with a base such as potassium tertiary butoxide to givea cyclopropane followed by treatment with methyllithium. A furtherprocess involves treatment of an olefin with tetrabromomethane andmethyllithium.

The reaction of the invention must be carried out under neutral or basicconditions since it does not occur in an acidic environment. Aconvenient method for the introduction of formaldehyde to the allene isto employ a base polymerized polyformaldehyde from which formaldehyde isgenerated at the temperature employed in the reaction. Other varietiesof polyformaldehyde, even those containing acids, are suitable ifsufficient quantity of an acid acceptor, suitably 1,8-bis-(dimethylamino)-naphthalene, is present to insure absence of acid duringthe reaction. However, gaseous formaldehyde can be introduced during thereaction but further equipment, such as pressuring and meteringequipment'may be needed.

Formaldehyde is generally employed in a molar equivalent amount to thatof the allene. The formaldehyde may be present in excess to obtainhigher conver- The reaction is generally conducted at l50-22()C. Underthese conditions, formaldehyde is a gas and pressure is employed toretain it and lower allenes in contact with each other.

The time employed for the reaction depends upon the temperature. Ingeneral times of from l-l0 hours are used.

The reaction involved may be represented by the wherein the R groups areas defined above.

The alcohol product can be isolated by distillation or.

chromatographic techniques. When tetramethylallene is used, R is H and RR and R are Ch in the above formulas. When R is phenyl, R and R are H,and R is CH the alcohol obtained is 2-(B-styryl)-2-butenol.

Higher alcohols, i.e., where R is alkyl only, produced by the reactionof the invention can be isomerized andwherein R is the residue of R. Therearranged alcohols can be separated by conventional techniques, e.g.,distillation and chromatography.

In general, heat dehydrates the rearranged alcohol to give thecross-conjugated triolefin having the structure CH 11 2 n ca=c-c-c-cim aI 5 R2 n In the latter formula when tetramethylallene is used as thestarting material, the novel and useful products have the structures andproperties as given in Example 3.

Specific Embodiments of the Invention The following examples areillustrative of the invention. All parts and percentages are byweightunless stated otherwise.

EXAMPLE I Tctramethylallene and Formaldehyde H 6.95, 7.3, 8.8, 9.92, andll.2[L; uvkmax 227 my. R Rq CH (=13824). 3

Anal. Calcd for C,,H C, 88.82; H, 11.18 C'H2OK 5 Found: C, 88.78; H,11.19 cfl3..('):c-c' C1-l3 C1120 150 C. CH2=('J-C=(IICH3 CH c 5 CH CHFurther distillation gave 4 ml bp 64/47 (n 1.4562) 3 3 3 3 and 3.2 ml bp578/24 11 14578) of 2,4-dimethyl- 3-methylene-4-penten-2-ol (11); massspectrum, t l 11 2- a m 24 ,325,232? 3 methyl M 126, and MH O, 108; nmr81.38 8,611 1.95 ((1,311), 2.20 (s,lH removed by D 0), 4.94 (m,2H) and Amixture of 6.6 ml of tetramethylallene and 1.5 g of 5,18 (m,1H); ir 2.9,3.2, 3.34, 6.08, 6.85, 7.3, 8.9, 10.5 vacuum dried polyformaldehyde(Alkaform oband 11.15p.; uvltmax 400-205 mp. tained by causticpolymerization of 37 percent aqueous formaldehyde) was heated at 150 ina sealed tube for 6 hrs. The contents were removed and separated by gaschromatography (using DC-200 on Chromsorb). Am'fl' Calcd for i ZU-n A 3,321%; :1 il iig Isolated were formaldehyde tetramethylallene v (16.9%),2,4-dimethyl-1,S-pentadiene (12.7%), 2,4- dimethyl-S,6-dihydro-2H-pyran,1,2-diisopropy1ideneof the m l ml 9 'd P P Y 4 3,3,4,4tetramethylcyclobutane (289%) and tetramethylcyclobutane distilled at 61.65 /3 n,, isopropenyl-3-methyl-2-buten-1-ol (32.8%). The latter 14922'g has mass spectrum of M =l26, MCH =111, MH- EXAMPLE 4 O=l08 and M(CH+l-l O)=93' nmr 81.71 2 3 2 9 (SJHMSL-M (SSHM '83 (m3H)52 -]2 (SJH,Isomenzatlon and Dehydrat on of Unsaturated Alcohol moved by D 0), 4.10(s,2H), 4.69 (m,1I-1), and 5.00 A solution of 100' g of2-isopropenyl-3-methyl-2- (n,1H); ir 11.2, 9.9, 7.32, 6.95, 6.12, 3.42and 3.0;t; buten-l-ol in 900 ml ether was passed through a 17.5 n=1.4718 and bp 174. cm X 10 mm column of Amberlyst l5 macroreticulateresin at approximately 3 ml/min. The effluent ex- EXAMPLE 2 clusive ofsolvent contained 2-isopropenyl-3-methyl-2- Tetramethylallene andFormaldehyde buten-l-ol, 2,4-dimethyl-3-methylene-4-penten-2-ol and2,4-dimethyl-3-methylene-1,4-pentadiene in the l ii i (2178 1 3 2, of aapproximate ratio 2/4/4. Distillation gave an apparent (s g d if a f gzf i l y azeotrope of the latter triene and water at a pot temperth'l moes h d t l'l T i l z ature of 110C. and head temperature of 82 84C. lens si t d ij m t a 5 am 655 S t 33 8' This was dried over magnesiumsulfate and redlstilled C ave an ea 6 er Qgenous pressure a to yield49.5 g of this triene, bp 100102C. and 18 g for 6 hours, cooled anddischarged. Gas chromato- Ofa colorless elastomeric polymer as residue.graphic assay against standards mdlcated that the product consisted of30.2% 1,2-diisopropylidene-3,3,4,4- EXAMPLE 5 tetramethylcyclobutane,53.6% 2-isopropenyl-3- Mthllauene and Formaldehl dc .1methyl-2-buten-l-ol, 6.4% 2-isopropenyl-3-methyl-2- H,cH=c=cH,+ c11 0 CH=C.(CH OH)CH=CH butenyl-l formate, 2.1% 2,2,4-trimethyl-5,6-dihydro- 1ll ZH-pyran and 7.7% 2,4-dimethyl-1,3-pentadiene. Distillation gave173,q g, bp 96-97C./3 mm. of substanwhen h general Procedure of Example2 s tially pure 2-isopropenyl-3-methyl-2-buten-1-01 correpeatedmethylanene .there was Obtamed Spending to a yield of 495 percent2-methylene-3-buten-l-ol (11) as shown by gas chromatographic analysis.The formate has a fruity odor and 1S stable at about 150C EXAMPLE 6EXAMPLE 3 lsomerization and Dehydration of Unsaturated Alcohol W CH CHC(CH oH ici li c H A solution of 26.5 g of 2-isopropylidene-3-methy1-2-l a z a 11 z 2 9H EH H C H C C(CH OH H C C C CH 3 crr o n c ca H c 0H 3I II III 81.88 (41,611), and 4.99 (m,6H); ir 3.22, 5.52, 6.1, 6.3,.

When the general procedure ofExample 2 was. repeated with 2,3-pentadiene(1), there was obtained 2-vinyl-2-buten-1-ol (11).

EXAMPLE 7 When the general procedure of Example 2 was repeated with3-methyl-l,2-butadien e (1), there was ob- B-Methy .-l,2-butadiene andFormaldehyde I II tained 2-isopropenyl-2-propen-l-ol (II).

The cross conjugated diene III produced in Example 3 can be used invarious reactions as shown by the following three examples:

EXAMPLE A Anal. Calcd for C I-MN C, 71.17; H, 5.12; N,

Found: C, 71.2 5.25

EXAMPLE B When 4.32 g of 2,4-dimethyl-3-methylene-1,4- pentadiene wasrefluxed for 8 hrs. with 3.92 g of maleic anhydride in about 25 ml ofacetonitrile, there was obtained a viscous oil after evaporation ofacetonitrile. The product has n 1.5071, it 5.5, 5.68 (C=O), 6.2. 11.2(C=C), and 10.1, 10.75 (COC). It crystallized to a colorless solid, mp5152.

Anal. Calcd for C H O C, 69.

89;H, Found: C,6 .43

This corresponds to the structure EXAMPLE C When fractions from Example3 containing 2,4- dimethyl-3-methylene-1,4-pentadiene were heated atatmospheric pressure and distilled at 96104 there was obtained a residuein the still pot. This was dissolved in methylene chloride, precipitatedand washed with methanol and dried. The product was polymeric (similarto high molecular weight polyisoprene) and had ir absorption at 6.15 and1125p. Treatment of a solution in methylene chloride withtetracyanoethylene gave a Diels-Alder polymeric'adduct (after momentarycoloration). m-Phenylene-bis-maleimide (10 percent by weight) ofpolymerwas added to a methylene chloride solution of this polymeric adduct andthe solution evaporated to produce a film. When the film was heated afew minutes at 190, a substantially colorless and insoluble film wasobtained.

The various alcohols produced by the invention, as for example,2-isopropenyl-3-methyl-2-buten-l-ol, can be converted to esters by knownmethods. Higher esters, e.g., of phthalic acid, are particularly usefulas plasticizers, e.g., for polyvinyl chloride. The isomeric alcohol,2,4-dimethyl-3-methylene-4-penten-2-ol, obtained by acid rearrangementcan also be converted to phthalate esters useful as plasticizers forvinyl resins.

The rearranged dehydration product 2,4-dimethyl-3-methylene-1,4-pentadiene is new and has crossconjugation. Ithomopolymerizes thermally to a high molecular weight elastomericmaterial e.g., 20,000 (by gel phase chromatography) which is much likepolyisobutene but is readily attacked by dienophiles. Thiselastomericmaterial can crosslink to a colorless vulcanizate with such materials asthe phenylene bismaleimides. Polymers can be obtained also by anionicand cationic processes. The anionic polymer prepared is not clearlydistinguishable from the thermal polymer by nmr but is non-elastomericwith a melting point just over C. Further, it does not readily reactwith dienophiles. Cationic polymers are of low molecular weight. The nmrdata shows they are not 1,2-polymers since l,2polymers potentiallyavailable would show four vinylic protons while only two appear.

In contrast to these properties, a known crossconjugatedplefin,3-methylene-l,4-pentadiene has not been shown to homopolymerize. Agelatinous material and oily substance were obtained. The latter ispresumably the dimer since the monomer was obtained on heating.

The new 3-methylene-2,4-dimethyl-l,4-pentadiene produced in thisinvention undergoes Diels-Alder addition for example with benzophenone.With the latter, adducts are capable of further self-condensation togive inert polymers.

1 claim:

l. 2,4-Dimethyl-3-methylene-1,4-pentadiene.

1. 2,4-DIMETHYL-3-METHYLENE-1,4-PENTADIENE. 